Antifreeze formulation containing glycerol

ABSTRACT

An antifreeze is provided for deployment in wet sprinkler systems located in cold environments. The antifreezes allows for the wet sprinkler system to be actuated under temperatures below 32° F. Wet sprinklers, methods of preventing wet sprinklers from freezing and methods of extinguishing fires also are provided.

This application claims priority to U.S. Provisional Application Nos. 62/513,000 filed May 31, 2017, 62/513,043 filed May 31, 2017, and 62/513,078 filed May 31, 2017.

TECHNICAL FIELD

The present invention relates generally to antifreeze formulations (liquid freeze protectants) for deployment in fire protection sprinklers and systems. Methods of preventing freezing and methods of extinguishing fires, as well as fire protection sprinklers and systems, also are provided.

BACKGROUND ART

Fire protection sprinklers are often needed to be located in cold environments where the temperature is subject to falling below the freezing point of water (32° F., 0° C. at sea level), referred to herein as a freezing temperature. Such cold environments include open areas, freezers, cold rooms, passageways, or other areas exposed to freezing temperatures, such as unheated buildings in freezing climates or cold-storage rooms. If a conventional sprinkler system is located in such a cold environment, the water will freeze in the sprinkler head and/or pipe and render the sprinkler unable to actuate or damage the sprinkler and/or piping.

Conventional sprinkler systems are fully filled (charged) with liquids (for example, water) and are referred to as “wet sprinkler systems.” As is known in the art, these systems include sprinkler heads and piping.

One approach for dealing with cold environments is referred to as a “dry sprinkler system.” Dry sprinkler systems are designed such that in the unactuated state, the water is kept out of the portion of the system that is located in the cold environment. Only upon activation does the water enter the portion of the system that is located in the cold environment. Dry sprinklers and sprinkler systems are disclosed in, for example, U.S. Pat. No. 7,559,376, and also include sprinkler heads and piping.

Wet sprinklers, on the other hand, are designed to be filled with a liquid when in the unactuated state. For wet sprinklers that are not placed in cold environments, the sprinkler can be filled with water.

Another approach for cold environments is the deployment in wet sprinkler systems of liquids having freezing points below the freezing point of water, and often are referred to as “antifreezes” or “liquid freeze protectants.” Early industrial antifreezes included the use of alcohols, such as methanol. Methanol, however, is flammable, toxic, and tends to be corrosive. Ethylene glycol and propylene glycol have supplanted methanol as an antifreeze.

The National Fire Protection Association (NFPA) has permitted antifreeze in sprinkler systems since at least as early as 1952. Arvidson, J. Fire Protect. Eng. 21(2):115-32 (2011). The NFPA currently permits a maximum of 38% by volume propylene glycol and a maximum of 48% by volume glycerin (glycerol) for fire sprinklers, and 48% vol. glycerin and water antifreezes are currently on the market. However, these two water additives, at their highest allowable concentrations have freezing points of 0° F. (propylene glycol) and −15° F. (glycerin). The field, however, has experienced various difficulties with these chemical components. First, propylene glycol cannot be used in systems having chlorinated polyvinyl chloride (CPVC) pipes. Moreover, these two components, at their highest allowable concentrations, have the potential of adding heat to a fire, which is measured as the “heat release rate.”

As reported by Arvidson, antifreezes have resulted in flashovers upon sprinkler activation. In a tragic incident in Truckee, Calif., an explosion occurred with a residential sprinkler system containing an antifreeze, which resulted in a fatality and another victim badly burned.

U.S. Patent Application Publication 2014/0138105 A1 discloses the use of carboxylate salts in propylene glycol and glycerol-containing fluids. This publication discloses glycerol concentrations up to 60% wt., the use of 5% wt. to 50% wt. of a carboxylate salt, like potassium formate, and a reserve of alkalinity to ensure that pH does not drop below 8.

It is therefore desirable to develop antifreezes that have lower concentrations of glycerin and salts, and yet have a lower freezing point while avoiding flashovers and adding less heat to fires. It is also desirable to avoid the use of ethylene and propylene glycol.

Glycerol (glycerin) has a molecular formula of C₃H₈O₃ and an IUPAC name of propane-1,2,3-triol. The structure is depicted below:

DISCLOSURE OF INVENTION

Preferred embodiments provide an antifreeze to be deployed (used) in wet sprinklers and systems. Additionally, the antifreeze can be deployed in wet and dry sprinkler systems where there may be a risk of freezing temperatures in parts of the system that would normally be filled with water (H₂O). Such a risk would include loss of heating in a warehouse or other structure, for example.

The antifreeze preferably is: 56% by volume water having a conductivity of no more than 500 μS/cm2 at room temperature; 44% by volume glycerol; 0.37% by weight potassium acetate; 0.09% by weight triethanolamine; 0.07% by weight trisodium citrate; and 0.07% by weight monosodium phosphate. The antifreeze has a pH of 7.9 and a freezing point at least as low as −20° F., preferably at least as low as −25° F., more preferably at least as low as −30° F. and still more preferably at least as low as −35° F. in the absence of deliberate seeding.

Preferably, the antifreeze has a heat release rate of no more than 10% higher than the heat release rate of at least one fire condition selected from the group of conditions consisting of (i) just prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze and (ii) the maximum running 60 second average heat release rate measured prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze.

The HRR can be determined using pendent sprinklers having a nominal K-factor of 4.2 and 8.0 gpm/(psig)^(1/2) on a supply piping arrangement comprising nominal 2-inch diameter steel pipe or larger connected to a pump system capable of providing the required test pressure and flow. The HRR determination can use a line-burner assembly with four spray nozzles arranged to discharge heptane at a total flow rate of 1.6 gpm (6.0 l/min) resulting in a fire having a nominal total heat release rate of 3,000 kW. The spray nozzles can be spaced 24 inches (610 mm) apart on the supply line and 24 inches (610 mm) above the floor.

According to preferred embodiments the antifreeze has an electrical shock risk similar to water when discharged onto energized equipment found in dwelling units

The wet sprinkler systems should have at least the portion of the wet sprinkler system that is exposed to the cold environment filled with antifreeze. The wet sprinkler systems also can have various portions to all portions of the wet sprinkler system filled with antifreeze.

According to preferred embodiments. the wet sprinkler system can limit temperatures in a ceiling space under 600° F. (316° C.) during a fire, where temperature is measured 3 inches below the ceiling space. Additionally, according to these embodiments, the wet sprinkler system during a fire can limit the temperature to no more than 200° F. (93° C.) at 5¼ feet (1.6 m) above the floor space. Moreover, according to such embodiments, the wet sprinkler system during a fire can limit the temperature to no more than 130° F. (93° C.) at 5¼ feet (1.6 m) above the floor space over a continuous 2-minute period. The wet sprinkler system, according to preferred embodiments, during a fire the temperature of the ceiling material ¼ inch (6.4 mm) behind the surface of the ceiling can be no more than 500° F. (260° C.).

Preferred embodiments also provide methods of preventing a wet sprinkler from freezing comprising the step of filling (deploying) a wet sprinkler with an antifreeze. Methods of providing for the extinguishment of a fire that occurs in a cold environment, wherein the method comprises the steps of: providing a wet sprinkler system that is at least partially located in cold environment; and deploying in the wet sprinkler system comprising an antifreeze as disclosed herein.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate exemplary approaches and protocols for testing embodiments of the invention, and together, with the general description given above and the detailed description given below, serve to explain the features, characteristics and capabilities of aspects of the invention. It should be understood that the preferred embodiments are teachings and examples of the invention as provided by the appended claims.

FIG. 1 depicts a heptane spray burner assembly illustrated in UL 2901.

FIG. 2 depicts a fire test arrangement illustrated in UL 2901.

FIG. 3 depicts a leakage test manifold assembly illustrated in UL 2901 with sprinklers in upright and pendent positions.

MODES FOR CARRYING OUT THE INVENTION

Antifreeze formulations, in general, take advantage of the phenomena that impurities lower the freezing point and increases the boiling point of a pure substance. When formulating antifreeze, it is therefore advantageous to add components that are soluble in water and can form a homogeneous solution. Components that are water soluble are ones that are polar, ionic and/or contain hydroxyl moieties (—OH groups). Ionic compounds (i.e., compounds having electrical charges that are either a positive, negative, or both) are more water soluble than their uncharged compounds. Moreover, ionic compounds add to the entropy of a solution, which contributes to freezing point depression.

All numerical limits and ranges set forth herein include all numbers or values thereabout or therebetween of the numbers of the range or limit. The ranges and limits disclosed herein expressly denominate and set forth all integers, decimals and fractional values defined by the range or limit. As shown by the following examples: (i), a range of 1 to 10, for instance, includes and discloses all values, for example 1, 2, 3, 3.5, 3.8, 4, 4.12, 5.981, 6.2, 7, etc. Ranges also can include negative values, if recited. A numerical limit of up to 10, for instance, includes and discloses all values, for example 0, 0.5, 1, 2, 3, 3.5, 3.8, 4, 4.12, 5.981, 6.2, 7, etc., and can include negative values depending on context, as is apparent to one skilled in the art (e.g., temperatures).

According to the invention, the water used to make the antifreeze should preferably be soft. A preferred conductivity range at room temperature for the soft water is about 0 to about 500 μS/cm², preferably 50 to 400 μS/cm², more preferably 100 to 350 μS/cm², still more preferably 200 to 350 μS/cm², and even more preferably 320 to 340 μS/cm² Values thereabout or there between these integers are included and can be employed according to the invention. Harder water can be softened by ion removal approaches, including distillation and reverse osmosis.

The term “about”(˜) in the context of numerical values and ranges refers to values or ranges that approximate or are close to the recited values or ranges such that the invention can perform as intended, such as having a desired rate, amount, degree or extent of components, conductivity, freeze protection, etc., as is apparent from the teachings contained herein. Thus, these terms encompasses values beyond those simply resulting from random and systematic error.

According to the invention, glycerol and other constituents are added to water to depress the freezing point, such as carboxylates. These other constituents include salts of organic acids having one or more carboxylic acid groups (—COOH). These acids tend to be classified as weak acids, and examples include formic acid (methanoic acid), acetic acid (ethanoic acid), propionic acid, butyric acid (butanoic acid), valeric acid (pentanoic acid), caproic acid (hexanoic acid), lactic acid (2-hydroxypropanoic acid), malic acid (2-hydroxybutanedioic acid), citric acid (2-hydroxypropane-1,2,3-tricarboxylic acid), benzoic acid (benzenecarboxylic acid), oxalic acid (ethanedioic acid), malonic acid (propanedioic acid), succinic acid (butanedioic acid), glutaric acid (pentanedioic acid), adipic acid (hexanedioic acid), pimelic acid (heptanedioic acid), suberic acid (octanedioic acid), azelaic acid (nonanedioic acid), sebacic acid (decanedioic acid). The cation of the salt can be an alkali metal, such as potassium (K⁺) or sodium (Na⁺). Other cations can be employed, however.

Glycerol should be present in a volume percentage ranging from 35 to 48%. Preferably, ethylene and propylene glycols are avoided according to the invention.

According to the invention, the antifreeze should have high ambient temperature stability, avoid the flashover problem of previous antifreezes and result in low increases in heat release rates (HRR). The antifreeze should have a hydraulic flow characteristics that allows transit through pipes and sprinkler assemblies, and preferably have hydraulic flow characteristics that are sufficiently similar to that of water to permit functionality. Additionally, corrosiveness and conductivity should be limited, and a stable pH, preferably near neutral should be maintained. The pH should be slightly acidic (about 6) to slightly basic (about 8). Preferred formulations have a pH ranging from 7 to 8, and more preferably 7 to below 8.

UL (Underwriters Laboratories) establishes and publishes criteria for antifreezes for deployment (use) in sprinklers. UL 2901 covers requirements for antifreezes used in fire sprinkler systems, which is hereby incorporated by reference in its entirety. Currently, no antifreezes are commercially available that meet UL 2901. The antifreezes according to the invention are contemplated to meet all or most requirements of the UL 2901, as well as possible changes in the future.

UL 2901 specifies the characteristics of acceptable antifreezes and sets forth testing procedures and parameters. Characteristics of an antifreeze meeting UL 2901 include:

-   -   High Ambient Temperature Stability based on Pour Point,         Viscosity, Specific Gravity, pH and Freeze Point after being         exposed to an elevated temperature for a period of time (158° F.         for 90 days is specified).     -   Temperature Cycling Stability based on Pour Point, Viscosity,         Specific Gravity, pH and Freeze Point after cycling at intended         use temperature extremes for 40 cycles.     -   Electrical conductivity not to exceed 1000 Siemens/cm² at room         temperature or exhibit an electrical shock risk similar to water         when discharged onto representative energized equipment         typically found in dwelling units. There is an emerging view         that the 1000 μSiemens/cm² level is too low, and therefore the         upper conductivity limit could be as high as 2000 μSiemens/cm²,         although upper limits of 1500 μSiemens/cm², 1400 μSiemens/cm²,         1300 μSiemens/cm², or 1200 μSiemens/cm² appear more likely.     -   Corrosion rate of at minimum and maximum concentrations not to         exceed 1.0 mils/year on steel, brass, stainless steel and any         other metal the sprinkler is composed.     -   Pit depth corrosion rate of at minimum and maximum         concentrations not to exceed 1.0 mils/year on steel, brass,         stainless steel and any other metal the sprinkler is composed         of.     -   Exposure to elastomeric materials to assess changes tensile         strength and elongation, volume and weight of the materials         (Natural Rubber, EPDM, BUNA-N, styrene butadiene rubber and any         other elastomer in the sprinkler.     -   Stress corrosion at minimum and maximum concentrations on steel,         brass, stainless steel and any other metal the sprinkler is         composed.     -   Galvanic action at minimum and maximum concentrations on steel,         brass, stainless steel and any other metal the sprinkler is         composed.     -   Compatibility with polymers (CPVC and cross-linked         polyethylene).     -   Acceptable toxicity.     -   Heat release rate of no more than 10% above the heat release         rate measured prior to the discharge of the antifreeze.     -   Firefighting effectiveness based upon nominal discharge         coefficient and nominal pressure.

As discussed above, salts of organic acids having one or more carboxylic acid groups (—COOH) are added. These salts lower the freezing point of the solution more than 5° F. than without the salts, and decrease the heat release rate when sprayed on fire. The reduction in freezing point is a colligative property of the solution, i.e., independent of chemical properties. For example, potassium acetate contributes two ions per molecule, which adds to the total entropy of the solution lowering the freezing point. While the addition of most hydrocarbons to a solution will add heat to a fire, potassium acetate and compounds having similar molecular structures reduce the heat of a fire by liberating carbon dioxide. Preferred percent range for salts of organic acids having one or more carboxylic acid groups are 0.01% to 1% wt., preferably 0.1% wt. to 0.5% wt. Betaine, such as trimethylglycine, are zwitterions and can be used in the same range of weight percentages.

Preferred salts include, but are not limited to:

To assist with pH stability, buffers also can be added to the antifreeze. Buffers for use according to the invention include citrate buffers, carbonate buffers, phosphate buffers, bicarbonate buffers and triethanolamine. Some buffers also provide the beneficial effect of evolving carbon dioxide during combustion. Preferred percent range of buffers are 0.01% to 1% wt., preferably 0.1% wt. to 0.5% wt.

When the antifreeze is deployed in a wet sprinkler system, at least the portion of the wet sprinkler system that is exposed to freezing temperatures is filled with the antifreeze. The entirety (or substantial portions thereof) of the wet sprinkler system can be filled with the antifreeze.

The invention is further described by the following examples, which are illustrative of the many aspects of the invention, but do not limit the invention in any manner. Water for the below formulas was sourced from Marinette County, Wisconsin. The water is soft, and has a conductivity of about 320 to 340 μS/cm² (68° F. to 79° F.).

An antifreeze according to the present invention can meet the following characteristics:

(A) Conductivity at room temperature less than 2000 μS/cm², preferably less than 1500 μS/cm², still preferably less than 1400 μS/cm², still preferably less than 1300 μS/cm2, still preferably less than 1200 μS/cm², still preferably less than 1150 μS/cm², more preferably less than 1100 μS/cm², more preferably less than 1075 μS/cm² and still more preferably less than 1050 μS/cm² and/or exhibit an electrical shock risk similar to water when discharged onto representative energized equipment typically found in dwelling units. (B) A heat release rate of no more than 20% above the heat release rate measured prior to the discharge of the antifreeze, preferably no more than 15% above the heat release rate measured prior to the discharge of the antifreeze, and still more preferably no more than 10% above the heat release rate measured prior to the discharge of the antifreeze. Current and emerging approaches to evaluating heat release rates are discussed in greater detail below. (C) A stable pH ranging from about 6 to about 8, and preferably neutral to below 8. (D) A freezing point that is lower than −10° F., preferably lower than −15° F., preferably lower than −20° F., more preferably lower than −25° F., still more preferably lower than about −30° F., yet more preferably −35° F., and even lower. (E) Viscosity—The viscosity should be such that the antifreeze can flow through the pipes and sprinklers. Preferably between 0.8 to 120 cP (centipoise), more preferably between 0.85 and 110 cP, and still more preferably between 0.89 and 100 cP.

The invention is further described by the following examples, which are illustrative of the many aspects of the invention, but do not limit the invention in any manner.

Example 1

The formula of Example 1 (Formula 1) is as follows:

56% vol. soft water (50.22% wt.)

44% vol. glycerol (49.35% wt.)

0.37% wt. potassium acetate

0.09% wt. triethanolamine

0.07% wt. trisodium citrate

0.07% wt. monosodium phosphate

Formula 1 has a conductivity of 1008 μSiemens/cm² at 78° F., a pH of 7.9 and a freezing point of −30° F. without deliberate seeding. A repeated testing yielded a conductivity of 986 μSiemens/cm² at 78° F., a pH of 7.9 and a freezing point of −36° F. without deliberate seeding.

Example 2—Testing According to UL 2901 and UL 1626

Testing of antifreeze is to be conducted according to UL 2901, which refers to and is based on UL 1626 and other standards. UL 2901 and UL 1626, and standards referenced therein, and hereby incorporated by reference.

A sprinkler discharging the most concentrated antifreeze solution shall not cause the total heat release rate from a heptane spray fire to increase by more than 10 percent above the heat release rate measured just prior to the discharge of the antifreeze solution, for any consecutive 15 second period throughout the antifreeze solution discharge.

Tests are to be conducted using open standard spray pendent sprinklers having a nominal K-factor of 4.2 and 8.0 gpm/(psig)^(1/2). The sprinklers are to be installed onto a supply piping arrangement consisting of nominal 2-inch diameter steel pipe or larger connected to a pump system capable of providing the required test pressure and flow. An electronic pressure transducer is to be installed in the supply piping at a distance not greater than 10 feet upstream from the sprinklers. The pump is to be connected to a supply of antifreeze solution that is of sufficient quantity to support the duration of the test.

The fire source is a line-burner assembly with four spray nozzles arranged to discharge heptane at a total flow rate of 1.6 gpm (6.0 l/min) resulting in a fire having a nominal total heat release rate of 3,000 kW. The spray nozzles are to be spaced 24 inches (610 mm) apart on the supply line and 24 inches (610 mm) above the floor. Metal grating having nominal dimensions of 94 inches long by 37 inches (940 mm) wide with a nominal 0.25 inch (6.4 mm) diameter wire mesh shall be installed above the heptane spray nozzles at a height of 38 inches (965 mm) above the floor. FIG. 1 provides details of the burner assembly.

Total Heat Release Rate Measurement (HRR)

The total heat release rate is to be measured using a paramagnetic oxygen analyzer, velocity probe, and a Type K thermocouple or equivalent under a calorimeter having diameter of not less than 25 feet (7.6 m). The instrumentation is to be located in the exhaust duct of the heat release rate calorimeter at a location that minimizes the influence of bends or exhaust devices. The heat release rate measurement system is to be calibrated using an atomized heptane diffusion burner. The calibration is to be performed using flows of 1, 2, 3 and 4 gpm (3.8, 7.6, 11.4 and 15.2 l/min) of heptane. A burner constructed with Model F-80-30, 70 degree PLP nozzles manufactured by Monarch Nozzle Co. has been found to be acceptable. The heat release rate is to be calculated at each of the flows as follows:

${HRR}_{t} = {16.54 \times 10^{3}V_{e}\frac{298}{T_{e}}A\frac{0.2095 - X_{02}}{1.076 - {1.36\mspace{14mu} X_{02}}}}$ Four tests are to be conducted in accordance with the below table, and FIG. 2 provides details of the test arrangement.

Nominal Sprinkler Sprinkler Elevation Sprinkler inlet Test K-factor Above the Floor Pressure Range Test gpm/(psig)^(1/2) feet (m) psig (kPa) 1 4.2  8 (2.4) 10-150 (69-1034) 2 4.2 20 (6.1) 10-150 (69-1034) 3 8.0  8 (2.4) 10-100 (69-690)  4 8.0 10 (6.1) 10-100 (69-690) 

After the data collection system is operating, the spray from the four-nozzle spray burner is to be ignited and then allowed to burn freely for 120 seconds while flowing a total of 1.6 gpm (6.0 l/min) of heptane through the line burner assembly. After the 120 second free-burn period, the antifreeze solution is to be discharged through the open sprinklers starting at flowing pressure of 10 psig (69 kPa) and then gradually increasing the pressure to the maximum pressure specified in the above table. At nominal pressure increments of 10 psig (69 kPa), the pressure is to be maintained at each test pressure for a nominal dwell time of 10 seconds before increasing the pressure to the next incremental pressure value. Total heat release rate measurements shall be recorded continuously throughout the duration of the test.

The emerging approach to evaluating heat release rates better takes into consideration the intrinsic variability of heptane burners. The approach modifies UL 2901 to the following:

a sprinkler discharging the most concentrated antifreeze solution shall not cause the total heat release rate from a heptane spray fire to increase by more than 10 percent above the maximum running 60 second average heat release rate measured prior to the discharge of the antifreeze solution, for any consecutive 15 second period throughout the antifreeze solution discharge. Based on a one second scan interval, the running 60 second average heat release rate for the test shall be calculated as follows:

${HRR}_{60\mspace{11mu}{avg}} = {\frac{1}{60}{\sum\limits_{i = n}^{i = {n + 59}}{HRR}_{i}}}$ In which:

-   -   HRR_(60 avg) is the 60 second average of the Total Heat Release         Rate     -   n is the test time scan number (n=1, 2, 3 . . . etc.) measured         in seconds.         -   n should be between:             -   n=0 seconds; defined as time zero which is the ignition                 of the burner assembly and             -   n=61 seconds (test time of 120 seconds); time at which                 the antifreeze solution is first discharged.                 The maximum running 60 second average heat release rate                 is the maximum value of HRR_(60 avg) during the time                 period described above.

Fire Fighting Effectiveness

When discharging the most concentrated solution of antifreeze, representative residential sprinklers shall demonstrate compliance with the fire test requirements described in the Fire Test Section of the Standard for Residential Sprinklers for Fire Protection Service, UL 1626 (which is incorporated by reference), when tested as follows:

The test room for these tests is to be configured based upon a rated sprinkler coverage area of 16 feet by 16 feet (4.9 m by 4.9 m). Recessed pendent and horizontal sidewall residential sprinklers that have previously demonstrated compliance with the fire tests specified in UL 1626 using water, are to be utilized for these tests. The following tests are to be conducted in accordance with the Fire Test Section of UL 1626 except that the most concentrated solution of antifreeze is to be discharged from the sprinkler in lieu of water:

-   -   (a) Recessed pendent sprinkler having a nominal discharge         coefficient of 4.9 tested with nominal pressure of 7 psig (48         kPa) at the sprinkler inlet with the frame arms orientated         perpendicular to the short wall;     -   (a1) an alternative approach for (a) is emerging where the         recessed pendent sprinkler having a nominal discharge         coefficient of 4.9 and 175° F. (79° C.) temperature rating         tested with the frame arms orientated perpendicular to the short         wall. First head operation will be at a nominal pressure of 13.5         psig (93 kPa) and pressure with two heads operating will be at a         nominal pressure of 7 psi (48 kPa);     -   (b) Recessed pendent sprinkler having a nominal discharge         coefficient of 4.9 tested with nominal pressure of 100 psig (690         kPa) at the sprinkler inlet with the frame arms orientated         parallel to the short wall;     -   (c) Recessed horizontal sidewall sprinkler having a nominal         discharge coefficient of 4.2 tested with nominal pressure of 23         psig (159 kPa) at the sprinkler inlet with the test fire located         on the far wall (opposite of the wall in which the sprinklers         are installed);     -   (c1) an alternative approach for (c) is emerging where the         recessed horizontal sidewall sprinkler having a nominal         discharge coefficient of 4.2 and 175° F. (79° C.) temperature         rating is tested with the test fire located on the far wall         (opposite of the wall in which the sprinklers are installed).         First head operation will be at a nominal pressure of 30 psig         (207 kPa) and pressure with two heads operating will be at a         nominal pressure of 23 psi (159 kPa); and     -   (d) Recessed horizontal sidewall sprinkler having a nominal         discharge coefficient of 4.2 tested with nominal pressure of 100         psig (690 KPa) at the sprinkler inlet with the test fire located         on the far wall (opposite of the wall in which the sprinklers         are installed).         The flowing pressures indicated above are to be based upon using         an adjusted discharge coefficient (K-factor) for the sprinkler         calculated as follows:

$K_{A} = {7.94\mspace{11mu} K_{W}\sqrt{\frac{1}{\gamma_{A}}}}$ K_(A)=Sprinkler K-factor discharging the antifreeze solution K_(W)=Sprinkler K-factor discharging water γ_(A)=Density of the antifreeze solution at the temperature used for testing, lbs./ft³

The Fire Test, according to UL 1626, limits temperatures over defined periods of time at various locations of a fire test arrangement in a test room made of building materials and containing furnishings and/or other items. The test room is representative of enclosures, and comprises walls, floor(s), ceiling(s), and attendant spaces that are proximal to the wall, floor and ceiling, as apparent to the person skilled in the art, typically 12 inches or closer unless otherwise defined.

UL 1626 requires that a residential sprinkler shall limit temperatures when tested at each rated-spacing referenced in the installation instructions. Additionally, a maximum of two residential sprinklers shall operate. The sprinklers shall limit temperatures as follows:

(a) The maximum temperature 3 inches (76 mm) below the ceiling at representative locations shall not exceed 600° F. (316° C.).

(b) The maximum temperature 5¼ feet (1.6 m) above the floor shall not exceed 200° F. (93° C.).

(c) The temperature at the location described in (b) shall not exceed 130° F. (54° C.) for more than any continuous 2-minute period.

(d) The maximum ceiling material temperature ¼ inch (6.4 mm) behind the finished ceiling surface shall not exceed 500° F. (260° C.).

Viscosity at Temperature Limitations

The viscosity of each concentration of antifreeze solution shall be determined at the temperature limitations specified in the manufacturer's installation instructions and shall correspond to the viscosity specified in the manufacturer's installation instructions.

Viscosity shall be determined as specified in the Standard Test Method for Low-Temperature Viscosity of Lubricants Measured by Brookfield Viscometer, ASTM D2983, using antifreeze samples conditioned at the minimum and maximum use temperature limitations specified in the manufacturer's installation instructions for at least 16 hours.

Resistance to Leakage

When tested as described below, antifreeze solution filled and pressurized pipe assemblies with sprinklers attached shall show no signs of leakage for 30 days. Two pipe assemblies that have demonstrated the ability resist leakage when filled and pressurized with water, are to be filled with antifreeze solution and pressurized to 350 psig (2413 kPa). One pipe assembly is to be positioned with six nominal k=5.6 orifice sprinklers in the vertical upright position, and the second pipe assembly is to be positioned with six nominal k=5.6 orifice sprinklers in the vertical pendent position. See FIG. 3 for diagrams of the typical pipe assemblies to be used for testing. The pipe joints are to be prepared by applying three wraps of polytetrafluoroethylene (PTFE) pipe joint sealant tape to each male thread for the pipe and sprinklers prior to assembly. The sprinklers are to be assembled with a torque not exceeding 20 ft.-lb (27 N-m). The samples are to be examined at least weekly and at the end of the 30 day test period for evidence of leakage of solution at the pipe joints and sprinkler closure caps.

Example 3—Testing Results

Formula 1 was tested by pump method where the sprayer was pumped every 3 seconds to maintain relatively constant pressure.

Average number of values above Baseline HRR 110% baseline in kW (no 110% level Percentage of in continuous antifreeze over baseline test HRR over 15 second Formula applied) HRR 110% baseline periods 1 4.8 5.28 53.8% 7.4

Formula 1 would meet the UL criteria and/or emerging criteria on HRR. Another formula that utilized 59.1% wt water and 40.6% wt glycerin and 0.3% wt. potassium formate was tested, but would not meet the UL criteria on HRR.

Example 4—Freeze Testing Under ASTM D 1177-05

ASTM D 1177-05 provides a Standard Test Method for Freezing Point of Aqueous Engine Coolants. The standard defines freezing point as “the temperature at which crystallization begins in the absence of supercooling or the maximum temperature reached immediately after initial crystal formation in the case of supercooling.” Section 3.1.1. Supercooling is not always encountered if seed crystals form on their own, however. The methodology of ASTM D 1177-05 employs deliberate seeding to ensure the prevention of supercooling. The seeding is accomplished by the introduction to the test solution a wire that has a small amount of frozen test solution on its tip.

The ASTM D 1177-05 testing of Formula 1 resulted in a freezing temperature of −14.6° F.

While the present invention has been disclosed with reference to certain embodiments, numerous modifications, alterations, and changes to the described embodiments are possible without departing from the sphere and scope of the present invention, as defined in the appended claims. Accordingly, it is intended that the present invention not be limited to the described embodiments, but that it has the full scope defined by the language of the following claims, and equivalents thereof. 

What is claimed is:
 1. An antifreeze to be deployed in a wet sprinkler system, wherein the antifreeze comprises 56% by volume water having a conductivity of no more than 500 μS/cm² at a temperature of 68° F. to 79° F.; 44% by volume glycerol; 0.37% by weight potassium acetate; 0.09% by weight triethanolamine; 0.07% by weight trisodium citrate; and 0.07% by weight monosodium phosphate, wherein the antifreeze has a pH of 7.9.
 2. The antifreeze according to claim 1, wherein the antifreeze has a heat release rate of no more than 10% higher than a heat release rate of at least one fire condition selected from the group of conditions consisting of (i) just prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze and (ii) a maximum running 60 second average heat release rate measured prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze.
 3. The antifreeze according to claim 2, wherein the heat release rate is determined using pendent sprinklers having a nominal K-factor of 4.2 and 8.0 gpm/(psig)^(1/2) on a supply piping arrangement comprising nominal 2-inch diameter steel pipe or larger connected to a pump system capable of providing the required test pressure and flow.
 4. The antifreeze according to claim 2, wherein the heat release rate is determined using a line-burner assembly with four spray nozzles arranged to discharge heptane at a total flow rate of 1.6 gpm (6.0 l/min) resulting in a fire having a nominal total heat release rate of 3,000 kW.
 5. The antifreeze according to claim 4, wherein the spray nozzles are to be spaced 24 inches (610 mm) apart on the supply line and 24 inches (610 mm) above the floor.
 6. The antifreeze according to claim 1, wherein the antifreeze has an electrical shock risk similar to water when discharged onto energized equipment found in dwelling units.
 7. A wet sprinkler system comprising an antifreeze, wherein the antifreeze comprises 56% by volume water having a conductivity of no more than 500 μS/cm² at a temperature of 68° F. to 79° F.; 44% by volume glycerol; 0.37% by weight potassium acetate; 0.09% by weight triethanolamine; 0.07% by weight trisodium citrate; and 0.07% by weight monosodium phosphate, wherein the antifreeze has a pH of 7.9, wherein the antifreeze has a heat release rate of no more than 10% higher than a heat release rate of at least one fire condition selected from the group of conditions consisting of (i) just prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze and (ii) a maximum running 60 second average heat release rate measured prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze.
 8. The wet sprinkler system according to claim 7, wherein the entirety of the wet sprinkler system is filled with the antifreeze.
 9. The wet sprinkler system according to claim 7, wherein a portion of the wet sprinkler system that is exposed to a cold environment is filled with the antifreeze.
 10. The wet sprinkler system according to claim 7, wherein the wet sprinkler system can limit temperatures in a ceiling space under 600° F. (316° C.) during a fire, and wherein temperature is measured 3 inches below the ceiling space.
 11. The wet sprinkler system according to claim 7, wherein the wet sprinkler system during a fire limits the temperature to no more than 200° F. (93° C.) at 5¼ feet (1.6 m) above a floor space.
 12. The wet sprinkler system according to claim 7, wherein the wet sprinkler system during a fire limits the temperature to no more than 130° F. (93° C.) at 5¼ feet (1.6 m) above a floor space over a continuous 2-minute period.
 13. The wet sprinkler system according to claim 7, wherein the ceiling is composed of ceiling material, and wherein during a fire the temperature of the ceiling material ¼ inch (6.4 mm) behind a surface of the ceiling is no more than 500° F. (260° C.).
 14. A method of preventing a wet sprinkler from freezing comprising the step of filling a wet sprinkler with an antifreeze comprising 56% by volume water having a conductivity of no more than 500 μS/cm² at a temperature of 68° F. to 79° F.; 44% by volume glycerol; 0.37% by weight potassium acetate; 0.09% by weight triethanolamine; 0.07% by weight trisodium citrate; and 0.07% by weight monosodium phosphate, wherein the antifreeze has a pH of 7.9, wherein the antifreeze has a heat release rate of no more than 10% higher than a heat release rate of at least one fire condition selected from the group of conditions consisting of (i) just prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze and (ii) a maximum running 60 second average heat release rate measured prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze.
 15. A method of providing for the extinguishment of a fire that occurs in a cold environment, wherein the method comprises the steps of: providing a wet sprinkler system that is at least partially located in cold environment; and deploying in the wet sprinkler system comprising an antifreeze comprising 56% by volume water having a conductivity of no more than 500 μS/cm² at a temperature of 68° F. to 79° F.; 44% by volume glycerol; 0.37% by weight potassium acetate; 0.09% by weight triethanolamine; 0.07% by weight trisodium citrate; and 0.07% by weight monosodium phosphate, wherein the antifreeze has a pH of 7.9, wherein the antifreeze has a heat release rate of no more than 10% higher than a heat release rate of at least one fire condition selected from the group of conditions consisting of (i) just prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze and (ii) a maximum running 60 second average heat release rate measured prior to discharge of the antifreeze solution for any consecutive 15 second period throughout the discharge of the antifreeze. 